Vanadium Metal and Its Resource in China

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Vanadium is a rare metal, with chemical symbol V and atomic number 23. It is quite chemically stable, and is not oxidized at room temperature. Vanadium has a high degree of corrosion resistance to the salt solution and sea water. It does not react with alkaline solution and sulfuric acid, but it can be dissolved in hydrofluoric acid, hot concentrated sulphuric acid, nitric acid and aqua regia. Vanadium metal powder can be dissolved in molten alkali, potassium carbonate and potassium nitrate, forming vanadate and vanadium salts. Vanadium silicide and vanadium carbide have high hardness and chemical stability.

Vanadium is oxidized to vanadium pentoxide (V2O5) when the temperature is above 933K (660°C). It has quite high structural strength, but it is extremely flammable. With high toxicity of vanadium compounds, vanadium-containing dust can cause lung cancer after being inhaled. Generally, there is pentavalent vanadium existing among vanadium oxides. There are also diatomic-, trivalent- and tetravalent vanadium, and they are an easy transition to pentavalent oxide. Divalent and trivalent vanadium oxides are alkaline; pentavalent oxide is acidic; tetravalent oxide is both alkaline and acidic.

Vanadium generally exists in the form of compounds. There are about 65 species of vanadium compounds in nature. Vanadium minerals are generally symbiotic with other metal minerals. There are a lot of vanadium exist in bauxite, petroleum, coal and oil shale. Besides, vanadium is found on the surface of the Sun and some stars by the spectral analysis.

Blunt vanadium metal is obtained by calcium reacting with vanadium pentoxide in the steel container. After washing, vanadium metal particles obtained melt into blocks in the vacuum furnace, and the metal thus obtained containing 99.99% of vanadium. However, the majority of vanadium is from other mineral’s by-products during processing.

Stone coal is inferior anthracite with low carbon-containing and calorific value, and is also a low-grade ores both polymetallic and symbiotic. Among the stone coal, vanadium is one of the most important valuable metal elements. Stone coal containing vanadium can be found more than 20 provinces throughout China, mostly in economically backward areas. According to statistics, the total reserve of vanadium in stone coal is seven times more than that of in vanadium-titanium magnetite well-known all over the world. Only in a length of more than 1,600 km of stone coal mine from Zhejiang to Guangxi province, there is more than 100 million tons of vanadium pentoxide. This shows that to exploit the rich vanadium-containing stone coal will bring in great economic potential and social benefits.

China is expected to become the world’s most promising market of vanadium in the future. Only to satisfy vanadium products consumed in steel production, vanadium production shall increase annually by more than 30%. However, with the continuous expansion of China’s domestic demand for vanadium products, the growth in domestic output of vanadium products is difficult to meet the growth in demand. In 2005, China had changed from an exporter to a net importer of vanadium products.

China has very rich vanadium resources, especially Chinese unique vanadium mine – stone coal in quite large reserve, but due to its low grade, it is difficult to exploit and use. In recent decades, Chinese vanadium extraction technology has made great progress, and is also a leader all over the world. But problems still exist, such as low extraction rate, low level of industrialization, serious environmental pollution, etc. Therefore, developing new techniques and technology to extract vanadium from stone coal efficiently and environmentally friendly has very broad research prospects.